If you have one of those stereos that was released in that awkward time between CDs and MP3 players, then it might be missing the now-standard auxiliary port for easy playback. Redditor Esplodies found themselves in this exact situation, and cleverly hacked together an auxiliary port for about $2.50 that works on some older CD players with a CD changer output.

This trick only works on CD players that don't have an aux port, but it's surprisingly easy to do. Esplodies used a CD-ROM audio cable and a resistor to plug into the rear CD changer port of the CD player. Then, they just wired that up to an auxiliary port, drilled a small hole in the front of the stereo, and that was it. It'll only work on a few different models of stereos, but if yours doesn't fit the bill, you can do it with a little solder, or go all out and add Bluetooth instead. Head over to Reddit for the full picture guide.